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VU

Socotra Cormorant Phalacrocorax nigrogularis

JustificationThis species is listed as Vulnerable because it has a small range, which is suspected to be undergoing a continuous and rapid decline, largely because of infrastructure and residential development, disturbance at its nesting colonies, exploitation, and marine oil pollution.

Identification80 cm. Large, blackish cormorant with bronze-green sheen on back and wings. In breeding season, becomes more glossy, with fine, white flecks on neck. Similar spp. Great Cormorant P. carbo is larger, with stouter bill and white face and chin-patch.

Distribution and populationPhalacrocorax nigrogularis occurs in two subpopulations (Gallagher et al. 1984). The northern one breeds on islands off the Persian Gulf coasts of Bahrain, United Arab Emirates (UAE), Saudi Arabia, Qatar and possibly Iran (breeding not confirmed since 1972) (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996). The southern subpopulation is apparently much smaller and breeds on one or more islands off the Arabian Sea coast of Oman and in the Gulf of Aden off Yemen (c.60,000 birds in total) (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996, Jennings 2000). Breeding was confirmed at Socotra for the first time in March 2005, when a colony of c.500 birds was found on the islet of Saboniya (S. Aspinall in litt. 2007), and there is now known to be a population of c.6250 pairs (Jennings 2010, R. Porter in litt. 2012). There is no evidence of birds moving between the two subpopulations, although this could be taking place (Baha El Din 1991). The overall population is estimated at 110,000 pairs (Jennings 2000) (330,000 [Jennings 2000] to fewer than 500,000 [H. King in litt. 2005] individuals). The species has a very small area of occupancy within its limited breeding range, which has declined rapidly largely because of human disturbance and oil spills (Chiozzi et al. 2007). Only 13 colonies are known to be active at the present time (Symens et al. 1993, Aspinall 1996, H. King in litt. 2005), equivalent to nine locations. The three largest colonies contain at least 75% of the world population (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996), with that on the island of Suwad al Janubiyah (hereafter Suwad) in the Hawar archipelago being the largest (H. King in litt. 2005). In the northern population, c.12 colonies have become extinct (Symens et al. 1993, Aspinall 1996, H. King in litt. 2005) since the 1960s, representing a potential decline of up to c.80,000 pairs (c.26% of the subpopulation). In Saudi Arabia, the number of breeding pairs declined by more than 75% during 1980-1992 (Symens et al. 1993). Only a rare visitor to the Red Sea, with a single individual observed around 1897. It is fairly common along the coast and islands of central and southern Eritrea, particularly in winter, when 500-4,000 birds were observed, and is still present in summer in large numbers (more than 1,500 birds at a time) (Chiozzi et al. 2007). Suspected to breed off the Danakil coast, although no nesting islands located (Chiozzi et al. 2007).

Population justificationThe breeding population is estimated at 110,000 pairs (Jennings 2010).

Trend justificationIn the northern population, c.12 colonies have become extinct (Symens et al. 1993, Aspinall 1996, H. King in litt. 2005) since the 1960s, representing a potential decline of up to c.80,000 pairs (c.26% of the subpopulation). In Saudi Arabia, the number of breeding pairs declined by more than 75% during 1980-1992 (Symens et al. 1993). Declines are thought to be continuing due to coastal development, disturbance and marine pollution.

EcologyBehaviour This species is highly gregarious, occurring throughout the year in large aggregations (Johnsgard 1993, King 2004, Nelson et al. 2005). Roosts are tightly packed, occupying the smallest possible ground footprint, potentially to maximise shade to the feet (King 2004). Some seasonal movements are thought to occur, probably related to fish migrations (Symens et al. 1993, Aspinall 1996), where the species travels in large flocks (del Hoyo et al. 1992) within the Persian Gulf and the Arabian Sea. However it is difficult to separate seasonal movements from dispersal (Johnsgard 1993), and there is little conclusive information available regarding patterns of movement (del Hoyo et al. 1992). It occurs as a vagrant as far east as West India, and west to the African coast of the Red Sea (del Hoyo et al. 1992). The breeding season is variable with laying recorded in most months, but each colony is internally synchronised (del Hoyo et al. 1992). Breeding has been reported to occur on the Kuria Maria islands from June to October (Gallagher and Woodcock 1980), on Halne Island in the Persian Gulf from January to March (Meinertzhagen 1954), and on the islands off Saudi Arabia in April, May, September, October and November (Bundy et al. 1989). It is suspected that breeding occurs irregularly to in response to locally varying food availability (Johnsgard 1993). Habitat The species is exclusively marine and occurs within the range of productive upwellings (Nelson et al. 2005). Breeding It breeds on offshore islands and islets that have shores of level sand or gravel (del Hoyo et al. 1992). Nonbreeding Outside the breeding season it roosts on coastal cliffs and rocky islets (del Hoyo et al. 1992). Diet Its diet consists principally of small pelagic shoaling fish for which it dives from the surface to depths in excess of 18 m (King 2004). It is regularly seen drowned in fishing traps at various depths (King 2004). Information concerning prey species is scarce (Johnsgard 1993, Nelson et al. 2005) although sardines (sardinella spp.), scads (Selar crumenophthalmus and Atule mate), Silverside Atherinomorphus lacunosus, Spotted Half-beak Hemiramphus far and Streaked Rabbit-fish Siganus javus are probably among the species taken (King 2004). Foraging occurs offshore in large groups (Gallagher and Woodcock 1980), and is thought to be communal rather than cooperative (Nelson et al. 2005). Breeding Site Breeding occurs on shores of level sand or gravel, or gently sloping hills free from vegetation (Johnsgard 1993), since unimpeded access by foot is essential (Aspinall 1996). Nests consist of depressions in the substrate, or in small mounds of substrate, and occur at high densities (Nelson et al. 2005) in colonies that range in size from 50 to tens of thousands of pairs (Johnsgard 1993, Nelson et al. 2005).

ThreatsThe very high rate of coastal development on the breeding islands is the main threat, since colonies are displaced and may not be able to successfully relocate elsewhere (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996). Colonies suffer from frequent human disturbance, which allows wide-scale predation of eggs by large gulls Larus spp. (Gallagher et al. 1984, Symens et al. 1993, Aspinall 1996). The extinction of 12 colonies since the 1960s, is attributed to encroachment by development and prolonged human disturbance (H. King in litt. 2005). The species is very vulnerable to marine oilspills (Gallagher et al. 1984, Symens and Suhaibani 1993). For example, in August 1980 an oil-spill of about 20,000 barrels of light crude oil off the coast of Bahrain killed up to 1,000 birds, most of which were this species (Baha El Din 1991). As well as direct mortality, reduced immune function and reduced breeding success from oiling and ingestion, oil-spills also deplete fish stocks (Baha El Din 1991). As a piscivore the species is susceptible to other marine pollutants such as heavy metals and PCBs (Polychlorinated biphenyls), as well as neurotoxins (Baha El Din 1991). Potential threats are posed by fisheries (food depletion), introduced predators on breeding islands, the harvesting of chicks and eggs for food (Symens et al. 1993, Morris 1996, M. Jennings in litt. 2012), and persecution (Symens et al. 1993, Aspinall 1996, Morris 1996). The species is regularly found drowned in fishing traps (H. King in litt. 2005). Ectoparasites may be a problem in some colonies (Gallagher et al. 1984), causing breeding cormorants to desert sites or abandon their young to die (Gallagher et al. 1984). As a ground-nesting species, it is vulnerable to the effects of storms, such as the flooding of nests during heavy rains, as took place on Suwad in November 1997, and the sudden termination of breeding and mass abandonment of chicks, as occurred due to an isolated thunderstorm with strong winds on Suwad in April 2003 (H. King in litt. 2005).

Conservation Actions UnderwayCITES Appendix II. The species is legally protected in most range states (Symens et al. 1993), but not in UAE (Aspinall 1995). Research on the species has increased during the last 10 years, and specific conservation measures have been proposed and acted upon, including the protection of some breeding sites. More surveys are planned by the Eritrean Coastal, Marine and Island Biodiversity project to investigate further evidence of nesting (Chiozzi et al. 2007). Conservation Actions ProposedContinue basic research into its ecology across its range (Baha El Din 1991, Symens et al. 1993, Aspinall 1996). Continue monitoring throughout its range (Symens et al. 1993, Aspinall 1996). Protect important breeding colonies (Symens et al. 1993, Aspinall 1996). Adopt breeding islands as priority sites in existing oil-spill contingency plans (Symens et al. 1993, Aspinall 1996). Continue public awareness campaigns (Symens et al. 1993, Aspinall 1996). Investigate restoration of certain former colonies (Aspinall 1996).

Recommended citation
BirdLife International (2015) Species factsheet: Phalacrocorax nigrogularis. Downloaded from
http://www.birdlife.org on 03/08/2015.
Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 03/08/2015.

This information is based upon, and updates, the information published in BirdLife International (2000)
Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004)
Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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